Bioinformation measurement device

ABSTRACT

Bioinformation of a seated person is more accurately measured. A heartbeat measurement device for measuring heartbeat of a person seated on a vehicle seat has heartbeat sensors and a circuit substrate: the heartbeat sensors have leading wires which output electric signals corresponding to a heartbeat and constitute a transmission path for the electric signals; and the circuit substrate has input terminals which receives the electric signals output from the heartbeat sensors, and a differential amplifier which amplifies the electric signals input to the input terminals. The heartbeat sensors and the circuit substrate are disposed in positions adjacent to each other in the vehicle seat, and terminal portions of the leading wires come out from portions adjacent to the circuit board of the heartbeat sensors are connected to the input terminals in a state abutting the input terminals.

TECHNICAL FIELD

The present invention relates to a bioinformation measurement device,and particularly directed to a bioinformation measurement device formeasuring a bioinformation of a seated person who is seated on a seat.

BACKGROUND ART

Among devices which measure a bioinformation, there are devices whichmeasure a bioinformation of a seated person who is seated on a seat. Anexample of such devices is a device which measures a heartbeat of aseated person of a vehicle seat (see the Patent Literature 1). Themeasurement device described in the Patent Literature 1 measures aheartbeat of a seated person by using an electrostatic capacitivecoupling type sensor which detects a body potential of a seated person.

More specifically, in the measurement device described in the PatentLiterature 1, the electrostatic capacitive coupling type sensor, detectsa body potential of a seated person and outputs an electric signalaccording to the detected potential. The output signal from the sensoris finally received by an arithmetic device, after subjected to anamplification processing, a filter processing, etc. By analyzing awaveform etc. of the received electric signal, the arithmetic devicecalculates a heartbeat (strictly, a heart rate) of the seated personfrom the electric signal.

CITATION LIST Patent Literature

PATENT LITERATURE 1: JP 2013-220322

SUMMARY OF INVENTION Technical Problem

Incidentally, in the measurement device described in the Patent Document1, a circuit for amplifying the output signal from the sensor isinterposed between the sensor and the arithmetic device. However, themore the sensor is separated from the amplification processing circuit,the longer a route for transmitting an electric signal output from thesensor (a transmission path) becomes. The longer the transmission pathbecomes, the more easily a noise is superposed on the output signal fromthe sensor. If a noise is superposed on an output signal from a sensorin this way, it is concerned that a heartbeat measurement based on thesignal is affected by the noise.

As for a substrate constituting the circuit (a circuit substrate), it isdesirable that the substrate is disposed in a position where a size or aquality (for example, riding comfort) of a seat is hardly affectedthereby.

Thus, the present invention has been achieved in light of the problem,and an object thereof is to provide a bioinformation measurement devicecapable of measuring a bioinformation of a seated person moreaccurately.

In addition, another object of the present invention is to dispose acircuit substrate in a position where a size or a quality of a seat ishardly affected thereby.

Solution to Problem

According to the bioinformation measurement device of the presentinvention, the problem is solved by a bioinformation measurement devicefor measuring a bioinformation of a seated person who is seated on aseat, which is provided with: a sensor which outputs an electric signalaccording to a bioinformation, with a leading wire constituting atransmission path for the electric signal; and a circuit substratehaving an input terminal provided to receive the electric signal fromthe sensor, and an amplification unit which amplifies the electricsignal input to the input terminal, wherein the sensor and the circuitsubstrate are disposed in positions adjacent to each other in the seat;and in the sensor, a terminal portion of the leading wire come out froma portion adjacent to the circuit substrate is connected to the inputterminal in a state abutting the input terminal.

In the bioinformation measurement device of the present inventionconfigured as above, the sensor and the circuit substrate are disposedin positions adjacent to each other. In the sensor, a terminal portionof the leading wire, which is come out from a portion adjacent to thecircuit substrate, is directly connected to the input terminal of thecircuit substrate. This allows configuring a route (a transmissionpath), through which an output signal from the sensor is transmitted, asshort as possible. As a result, it is unlikely to generate thesuperposition of the output signal from the sensor and the noise, whichis caused by the long transmission path, and thus, it becomes possibleto effectively control an influence of the noise.

In the above described configuration, it is also preferred that thecircuit substrate is attached to the seat so as to be positioned in thewidth direction center of the seat.

In the above described configuration, a circuit substrate is attached tothe seat so as to be positioned in the width direction center of theseat. On the other hand, the width direction center of the seat is aposition which faces a center of the body (a median line) of a seatedperson while the seated person is seated on the seat. By utilizing suchpositional relationship, it becomes possible to easily dispose a circuitsubstrate to a position where a quality of a seat is hardly affectedthereby.

It is also preferred that the above described structure has a pluralnumber of the sensors, and the plural number of the sensors are disposedin a state arranged across a gap in the width direction of the seat, andthe circuit substrate is disposed within the gap, in a state sandwichedbetween the sensors.

In the above described structure, the circuit substrate is disposedbetween the sensors arranged in the width direction of the seat.Disposing the circuit substrate by utilizing the gap between the sensorsin this manner, it becomes possible to control upsizing of a seat due toattachment of the circuit substrate.

It is also preferred that; the above described structure is providedwith a guard ring disposed in a manner surrounding the sensor; thesensor is disposed along a face abutting a seated person of the seat;and the sensor, the guard ring, and the circuit substrate are disposedin a state arranged along the width direction of the seat.

In the above described configuration, since the sensor, the guard ring,and the circuit substrate are disposed in a horizontal arrangement, itbecomes possible to make more compact space for installing each of theequipment, as compared with a structure in which each of the abovedescribed equipment is disposed off front each other.

In the above described structure, it is also preferred that the circuitsubstrate is attached so as to be positioned in the width directioncenter of a seat back provided to the seat.

In the above described structure, the circuit substrate is positioned inthe width direction center of the seatback. Thus, when the back of aseated person leans on the seatback, the circuit substrate is located inthe same position as a site positioned between the right and left pairof erector spinae of the back of the seated person, in the seat widthdirection. This makes it hard for the circuit substrate to touch theback (specifically, a site corresponding to the right and left pair oferector spinae) of the seated person.

In the above described structure, it is also preferred that the circuitsubstrate is attached so as to be positioned in the width directioncenter of a seat cushion provided to the seat.

In the above described structure, the circuit, substrate is positionedin the width direction center of the seat cushion. Therefore, when thebuttocks of a seated person are put on the seat cushion, the circuitsubstrate is located in the same position as a site corresponding to thegluteal cleft portion of the buttocks of the seated person, in the seatwidth direction. This makes it hard for the circuit substrate to touchthe buttocks of the seated person.

In the above described structure, it is also preferred that the sensorand the circuit substrate are attached to each of the seat cushion andthe seatback provided to the seat, and a range in which the circuitsubstrate attached to the seat cushion is located in the seat widthdirection and a range in which the circuit substrate attached to theseatback is located in the width direction overlap with each other.

In the above described structure, location ranges in the seat widthdirection of the circuit substrate attached to the seat cushion and thecircuit substrate attached to the seatback are in substantially a sameposition in the seat width direction. In this manner, it becomespossible to attach the circuit substrate to each of the seat, cushionand the seatback, so as to be properly settled thereon. This allows anattachment work of the circuit substrate to be performed comparativelyeasily.

EFFECTS OF INVENTION

According to the present invention, it becomes possible to configure theroute for transmitting an output signal from the sensor as short aspossible, to effectively control a situation that a noise is easilysuperposed on an output signal from the sensor.

According to the present invention, it becomes also possible to easilydispose a circuit substrate to a position where a quality of a seat ishardly affected thereby.

According to the present invention, it becomes also possible to controlupsizing of a seat due to attachment of a circuit substrate.

According to the present invention, it becomes also possible to makemore compact space for installing each of the sensor, the guard ring,and the circuit substrate.

In addition, according to the present invention, the circuit substrateis located in the same position as a site positioned between the rightand left pair of erector spinae of the back of a seated person in theseat width direction, when the back of the seated person leans on theseatback, since the circuit substrate is disposed in the width directioncenter of the seatback. As a result, it becomes hard for the circuitsubstrate to touch the back of a seated person.

In addition, according to the present invention, when the buttocks of aseated person are put on a seat cushion, the circuit substrate islocated in the same position as a site corresponding to the glutealcleft portion of the buttocks of the seated person, in the seat widthdirection, since the circuit substrate is disposed in the widthdirection center of the seat cushion. As a result, it becomes hard forthe circuit substrate to touch the buttocks of a seated person.

According to the present invention, it becomes also possible to attachthe circuit substrate to each of the seat cushion and the seatback, soas to be properly settled thereon.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view showing a vehicle seat to which a bioinformationmeasurement device according to an embodiment of the present inventionis attached.

FIG. 2 is a front view of a sensor and a circuit substrate attached to aseat back.

FIG. 3 is a cross-sectional view of a sensor, and is a schematic viewshowing the A-A cross section in FIG. 2.

FIG. 4 is a view showing a structure of a circuit substrate.

FIG. 5 is a view showing a positional relationship of the back of aseated person, a sensor, and a circuit substrate.

FIG. 6 is a view showing a position of a spinous process in the spine ofa seated person.

FIG. 7 is a plan view of a sensor and a circuit substrate attached to aseat cushion.

FIG. 8 is a view showing a location range of a circuit substrate in eachof a seatback and a seat cushion.

FIG. 9 is a view showing a seatback of a vehicle seat according to asecond embodiment of the present invention.

FIG. 10 is a view showing a seat cushion of a vehicle seat according toa second embodiment of the present invention.

FIG. 11 is a view showing a sensor and a circuit substrate in the sideof the seat back, according to a second embodiment of the presentinvention.

FIG. 12 is a view showing a sensor and a circuit substrate in the sideof the seat cushion according to a second embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Hereinbelow, an embodiment of the present invention (the presentembodiment) is described. Incidentally, in the following, a seat mountedon a vehicle (hereinbelow, a vehicle seat) is described as a specificexample of a seat. However, the present invention can also be applied toa seat other than vehicle seats. For example, the present invention canalso be applied to a seat to be mounted on a conveyance other thanvehicles, or a seat to be used in a building such as a house or afacility.

In the following description, “seat width direction” corresponds to thewidth direction of the seat, more particularly, corresponds to thelateral width direction (right to left direction) of a vehicle seat.“Front to back direction” corresponds to the front to beck direction ofthe seat, and coincides with a traveling direction of the vehicle onwhich the vehicle seat is mounted. “Height direction” corresponds to thevertical direction of the seat, particularly, the height direction ofthe vehicle seat in a state capable of seating, and more particularly,the direction from the lower end toward the upper end of a seatback ofthe vehicle seat. Incidentally, in the following description, contentsconcerning a position, an orientation, or the like of each of equipmentare contents in a state that the equipment is attached to the vehicleseat.

Outline of Bioinformation Measurement Device According to PresentEmbodiment

First, outline of the bioinformation measurement device according to thepresent embodiment is described. The bioinformation measurement deviceaccording to the present embodiment is a heartbeat measurement device 1that measures a heartbeat of a seated person as a bioinformation of theseated person seated on a vehicle seat. More particularly, while aseated person is seated on the vehicle seat, the heartbeat measurementdevice 1 detects a body potential of the seated person with anelectrostatic capacitive coupling type sensor attached to the vehicleseat. Then, the heartbeat measurement device 1 measures a heartbeat ofthe seated person on the basis of an electric signal output by thesensor according to the body potential of the seated person.

A structure of the heartbeat measurement device 1 is outlined withreferring to FIG. 1. FIG. 1 is a front view of a vehicle seat S to whichthe heartbeat measurement device 1 is attached. Incidentally, thevehicle seat S has a structure substantially identical to that of apublicly known vehicle seat, except for a point that the heartbeatmeasurement device 1 is attached, thereto. That is, the vehicle seat Saccording to the present embodiment is provided with a seat back S1against which the back of a seated person leans, a seat cushion S2 thatsupports the buttocks of a seated person from below, and a headrest S3that supports the head of a seated person. The seatback S1 and the seatcushion S2 are each configured by placing a pad material in a framewhich constitutes a skeleton of the seatback S1 or the seat cushion S2,and covering surface of the pad material with a skin material.

The heartbeat measurement device 1 has sensor units 10A and 10B asillustrated in FIG. 1, and an ECU (Electric Control Unit) 2 as anarithmetic device, as main constituent elements. One sensor unit 10A andone sensor unit 10B are respectively attached to the seatback S1 and theseat cushion S2, as shown in FIG. 1. More particularly, one sensor unit10A is attached to a portion of the seatback S1, which is a portionfaced to the back of a seated person when the seated person is seated onthe vehicle seat S. The other sensor unit 10B is attached to a portionof the seat cushion S2, which is a portion faced to the buttocks of aseated person when the seated person is seated on the vehicle seat S.

Each of the sensor units 10A and 10B has an electrostatic capacitivecoupling type sensor (specifically, a heartbeat sensor 11 which will bedescribed later) which electrostatic-capacitively coupled to the body ofa seated person to detect a body potential of the seated person. Then,each of the sensor units 10A and 10B outputs an electric signalaccording to the body potential of the seated person detected by thesensor to ECU2.

Incidentally, in the structure illustrated in FIG. 1, each of the sensorunits 10A and 10B are respectively adhered to each surface (strictly,the face to come in contact with the body of a seated person) of theseatback S1 and the seat cushion S2, with being exposed. In such astructure, the electrostatic capacitive coupling type sensor provided toeach of the sensor units 10A and 103 is to be electrostatic-capacitivelycoupled the body of a seated person through a cloth of the seatedperson. However, this is not a limitation, and the sensor units 10A, 10Bmay be provided in a state sandwiched between the skin material and thepad material in each of the seatback S1 and the seat cushion S2. In sucha case, each of the sensor units 10A and 10B iselectrostatic-capacitively coupled the body of a seated person throughthe skin material and a cloth of the seated person.

The ECU2 receives an electric signal output from each of the sensorunits 10A and 10B, and analyzes the electric signal, to calculate aheart rate of a seated person. In this connection, although explanationof specific method of calculating the heart rate based on output signalsfrom the sensor units 10A and 10B is omitted, a publicly knowncalculation method (for example, the calculation method described in JFNo. 2015-123359) is available.

In the ECU2, when an output signal from the sensor unit 10A or 10B isanalyzed, the output signal is subjected to an amplification processing,a filter processing, or the like. That is, circuits for carrying outeach of the processing described above are incorporated in the ECU2, anda corresponding signal processing is performed in each of the circuits.In other words, in the present embodiment, the ECU2 has a function as aninstrumentation amplifier, to further amplify an electric signal whichhas been amplified by a differential amplifier 30 described later, andto subject the signal after amplified to a filter processing by using ahigh pass filter or a low pass filter.

In the present embodiment, the ECU2 is disposed in the backside (a lowerside) of the seat cushion S2, as shown in FIG. 1. As shown in the samefigure, between each of the sensor units 10A or 10B and the ECU2, cablesC for linking the two are laid. One end of each of the cables C isjoined into the ECU2, and the other end is connected to each sensor unit10A or 10B. Incidentally, the cables C are laid so as to go around fromthe front side (the exposed side) to the backside of the vehicle seat S,penetrating the skin material and the pad material which constitute theseatback S1 and the seat cushion S2, and as shown in FIG. 1.

Detailed Structure of Sensor Unit

Next, detailed structures of the sensor units 10A and 10B are described.First, the sensor unit 10A attached to the seatback S1 is described withreferring to FIG. 2. FIG. 2 is a view of a sensor unit 10A attached to aseat back S1, as viewed from the front (ahead) of the vehicle seat S.

As shown in FIG. 2, the sensor unit 10A has a right and left pair ofheartbeat sensors 11, a buffer circuit unit 21, and a base film 14 onwhich the heartbeat sensors 11 and the buffer circuit unit 21 areplaced. In addition, a guard ring 15 is formed on the base film 14.Hereinbelow, each portion of the sensor unit 10A is described in detail.

(Heartbeat Sensor 11)

The heart beat sensor 11 is an electrostatic capacitive coupling typesensor which is disposed on the front face (the contact face with aseated person) of the seatback S1 via the base film 14. The heartbeatsensor 11 detects a body potential of a seated person when the back ofthe seated person leans against the seatback S1, and outputs an electricsignal according to the detected result. Here, a body potential of aseated person generally changes according to a heartbeat (a heart rate)of the seated person, which means that the heartbeat sensor 11 outputsan electric signal according to a heartbeat of a seated person.

Incidentally, in the present embodiment, the heartbeat sensor 11 isinstalled in plural numbers, specifically, disposed in a right and leftpair (i.e., two), symmetrically, with having the center position of theseatback S1 in the seat width direction as a boundary. This is because,a potential difference (a potential difference signal) between electricsignals individually output from the right and left pair of heartbeatsensors 11 is required in measuring a heartbeat of a seated person.

Incidentally, the right and left pair of heartbeat, sensors 11 isattached to the seat back S1, so as to be arranged across apredetermined gap in the seat width direction. In this manner, when theback of a seated person leans on the seat back S1, the right and leftpair of heartbeat sensors 11 is located in positions across the heart ofthe seated person in the seat width direction.

In this connection, a width of the above described gap (a length in theseat width direction, which is represented by w in FIG. 2) is preferablyconfigured to be 80-150 mm. If the gap is configured to be in the abovedescribed range, when the back of a seated person leans against theseatback S1, each of the heartbeat sensors 11 faces to a sitecorresponding to the erector spinae of the back of the seated person,making it easy to contact with the site (i.e., the electrostaticcoupling is facilitated).

A structure of the heartbeat sensor 11 is described. Each of theheartbeat sensors 11 is formed of a sheet-shaped electrode, and has asubstantially rectangular external configuration, as shown in FIG. 1.Each of the heartbeat sensors 11 has an area and a capacitancesufficient to detect a body potential of a seated person.

The structure of the heartbeat sensor 11 is described more in detail.Each of the heartbeat sensors 11 is formed of a leading wire 12 and abase unit 13 that encloses the leading wire 12. The base unit 13 isformed of a substantially rectangular sheet and defines the outer shapeof the heartbeat sensor 11. In the present embodiment, the base unit 13has a laminated structure as shown in FIG. 3. FIG. 3 is across-sectional view of a heartbeat sensor 11, which is a schematic viewshowing the A-A cross section in FIG. 2.

As shown in FIG. 3, the base unit 13 has a lowermost layer 13 a, anintermediate layer 13 b, and an uppermost layer 13 c. The lowermostlayer 13 a is a resin film made of PET (Poly Ethylene Terephthalate).The intermediate layer 13 b is a resin film made of a carbon resin. Theuppermost layer 13 c is a coating film of a metal ink including bariumtitanate.

As shown in FIG. 3, the leading wire 12 is disposed between thelowermost layer 13 a and the intermediate layer 13 b. The leading wire12 is made of silver, and forms a transmission path for electric signalsgenerated by the heartbeat sensor 11 according to a body potential of aseated person. That is to say, an electric signal is transmitted throughthe leading wire 12 in the heartbeat sensor 11, and finally output tothe outside of the heartbeat sensor 11, through the terminal portion 12a of the leading wire 12.

Incidentally, as shown in FIG. 2, the leading wires 12 are wired in alattice shape in the base unit 13. That is, in the base unit 13, theleading wires 12 are wired correspondingly to the externalconfiguration. Specifically, the leading wires 12 is present in pluralnumbers in such a state that leading wires 12 disposed along thelongitudinal direction of the base portion 13 and leading wires 12disposed along the short side direction of the base portion 13 intersecteach other.

A portion corresponding to the terminal portion 12 a of the leading wire12 (in other words, a portion positioned in the most downstream side ofthe transmission path of the electric signal) is wired in a mannerdeviating from the other portions. Describing specifically withreferring to FIG. 2, a portion of the base unit 13 including theterminal portion 12 a of the leading wire 12 protrudes from the otherportion (substantially the rectangular portion), inward in the seatwidth direction. This protruding portion extends toward the buffercircuit unit 21, together with the terminal portion 12 a of the leadingwire 12. Then, the terminal portion 12 a of the leading wire 12 isjoined into a circuit substrate 22 provided in the buffer circuit unit21, more strictly, to an input terminal 23 of the circuit substrate 22.

As for the external configuration of the heartbeat sensor 11, arcuatenotches 13 x are formed in an outer edge portion of the heartbeat sensor11 (strictly, the base unit 13), as shown in FIG. 2. Specifically, eachtwo notches 13 x are formed on one end portion and the other end portionin the short side direction of the outer edge portion of the base unit13. Additionally, one notch 13 x is formed on one end portion in thelongitudinal direction of the outer edge portion of the base unit 13. Byforming the notches 13 x in this manner in several portions of the outeredge portion of the base unit 13, it becomes possible to alleviateinfluence to the heartbeat sensor 11, when the back of a seated personleans against the seatback S1.

Specifically, when the back of a seated person leans against theseatback S1, a load from the back of the seated person acts on theheartbeat sensor 11. Due to this load, the base unit 13 in the heartbeatsensor 11 is bent, and at this time, if a wrinkle is generated, theleading wire 12 is curved along the wrinkle. Then, a stress isconcentrated to the curved portion, causing a concern that the leadingwire 12 is disconnected. In contrast, in the present embodiment, sincethe notches 13 z are formed in the outer edge portion of the base unit13, when the base unit 13 is bent, the bending is not accompanied by awrinkle. In this manner, it becomes possible to effectively control thebending of the leading wire 12, and a disconnection caused thereby.

(Base Film 14)

The base film 14 is a substrate for attaching the right and left pair ofheartbeat sensors 11 to the front face (the backrest face) of theseatback S1. In the present embodiment, the base film 14 is formed of anacrylic film, and has a substantially square external configuration. Theheartbeat sensor 11 is adhered to the front face of the base film 14,and the back face of the base film 14 is attached to a predeterminedposition in the front face of the seatback S1.

As shown in FIG. 2, the base film 14 has an area sufficient to place theright and left pair of heartbeat sensors 11. That is, in the presentembodiment, two heartbeat sensors 11 are placed on a single base film14. For this, number of parts is reduced, as compared with a structurein which the base film 14 is provided individually to heartbeat sensors11. However, this is not a limitation, and the structure may also besuch that the base film 14 is separately provided individually to theheartbeat sensors 11.

In the base film 14, the portion positioned between the heartbeatsensors 11 is punched out in a substantially rectangular shape as shownin FIG. 2. In the upper side and the lower side of this punched outportion, linking units 14 a and 14 b that link between the heartbeatsensors 11 are formed. By linking the heartbeat sensors 11 with theselinking units 14 a and 14 b, it becomes possible to handle the right andleft pair of heartbeat sensors 11 integrally. For example, in anattachment work of the heartbeat sensors 11, it is possible to attachthe right and left pair of heartbeat sensors 11 integrally. However,this is not a limitation, and the structure may also be such that theright and left pair of heartbeat sensors 11 is separated, without beinglinked.

As shown in FIG. 2, arcuate notches 14 x are formed similarly in an edgeportion of the base film 14, in portions adjacent to the notches 13 xformed on the base unit 13 of the heartbeat sensor 11. In this manner,the base film 14 also bends without generating a wrinkle, when the backof a seated person leans against the seatback S1. As a result, itbecomes possible to more effectively control a bending of the leadingwire 12 which accompanies generation of a wrinkle, and a disconnectioncaused thereby.

(Buffer Circuit Unit 21)

The buffer circuit unit 21 relays data between the heartbeat sensor 11and the ECU2. This buffer circuit unit 21 amplifies an output signal (anelectric signal) from each of the heartbeat sensors 11, and outputs theamplified signal towards the ECU2. The buffer circuit unit 21 isdisposed between the heartbeat sensors 11 in the seat width direction.More particularly, the buffer circuit unit 21 is placed on the lowerside linking unit 14 b in the base film 14.

A structure of the buffer circuit unit 21 is described. The buffercircuit unit 21 is provided with a circuit substrate 22, an inputterminal 23, and an output terminal 24, as shown in FIG. 2. These piecesof equipment are housed in a substrate case 25 made of a resin.

The circuit substrate 22 is a portion forming a main body of the buffercircuit unit 21. An output signal (an electric signal) from each of theheartbeat sensors 11 is subjected to an amplification processing by thiscircuit substrate 22. More specifically, the circuit substrate 22 has adifferential amplifier 30 as an amplification unit, as shown in FIG. 4.An output signal from each of the heartbeat sensors 11, which has beeninput to the input terminal 23, is amplified by a function of thedifferential amplifier 30. In this connection, FIG. 4 is a schematiccircuit diagram showing a structure of the circuit substrate 22.

The circuit substrate 22 is provided with an impedance adjustment unit31 in a preceding stage of the differential amplifier 30, as shown inFIG. 4. This impedance adjustment unit 31 is a circuit for matching animpedance value at a time when one of the right and left pair ofheartbeat sensors 11 outputs an electric signal with an impedance valueat a time when the other outputs an electric signal.

Incidentally, as shown in FIG. 2, the circuit substrate 22 is in a statesandwiched between the pair of the right and left heartbeat sensors 11in the seat width direction, and disposed in a gap formed between theheartbeat sensors 11. In this manner, by disposing the circuit substrate22 utilizing the gap between the heartbeat sensors 11, the presentembodiment controls upsizing of the vehicle seat S due to attachment ofthe circuit substrate 22.

The input terminal 23 is a terminal to which an output signal from eachof the heartbeat sensors 11 is input, which is formed of a metal piece.The input terminal 23 is built to both ends of the circuit substrate 22in the seat width direction. Each input terminal 23 is disposed in aportion adjacent no a base unit 13 of a corresponding heartbeat sensor11 (strictly, a portion stretched inward in the seat width direction),as shown in FIG. 2. Then, the terminal portion 12 a of the leading wire12 enclosed in the portion adjacent to the input terminal 23 (in otherwords, the circuit substrate 22) of the base unit 13, is directlyconnected to the nearest input terminal 23.

That is, in the present embodiment, the terminal portion 12 a of theleading wire 12 is connected to an input terminal 23, in a stateabutting the input terminal 23. This shortens a transmission path for anoutput signal from a heartbeat sensor 11, as compared to a case whereanother leading wire is interposed between the terminal portion 12 a ofthe leading wire 12 and the input terminal 23. As the transmission pathis shortened, it becomes hard for a noise to be superposed on an outputsignal from a heartbeat sensor 11, which improves an accuracy inmeasuring a heartbeat of a seated person on the basis of the outputsignal.

In this connection, a method of joining the terminal portion 12 a of theleading wire 12 to the input terminal 23 is not particularly limited,but the terminal portion 12 a may be joined by using a caulker, or maybe joined by using a connector which is not illustrated.

The output terminal 24 is a terminal, from which an electric signalamplified by the differential amplifier 30 is output, which is formed ofa metal piece. To this output terminal 24, an end portion of a cable C(strictly, a core material of a cable C) is connected. Accordingly, anelectric signal output from the output terminal 24 is transmitted towardthe ECU2 through the cable C.

(Guard Ring 15)

The guard ring 15 is a patterned conductor provided in a mannersurrounding a heartbeat sensor 11, which controls a leakage current fromthe heartbeat sensor 11. This guard ring 15 is formed along edgeportions of the base film 14 (the inner edge portion and the outer edgeportion), over the entire edge portion, as shown in FIG. 2. In the basefilm 14, in portions corresponding to the linking units 14 a and 14 b,the guard ring 15 is formed over the entire surface (the front face) ofthe portions.

Incidentally, in the present embodiment, each of the heartbeat sensors11, the guard ring 15, and the circuit substrate 22 are disposed in astate horizontally arranged along the seat width direction, as shown inFIG. 2. This makes a space for installing each piece of equipmentcompact, as compared with a structure in which these pieces of equipmentare disposed in a state shifted from each other (strictly, a stateshifted in the height direction).

A sensor unit 10A configured as above appropriately detects a bodypotential of a seated person, when the back of the seated person leansagainst the seatback S1. Particularly, the sensor unit 10A is disposedin a position where a seated person hardly feels a foreign touch in theseatback S1. More specifically, the buffer circuit unit 21 including thecircuit substrate 22 is attached to the front face of the seatback S1 soas to be positioned in the center of the seatback S1 in the seat widthdirection (illustrated by a broken line in FIG. 2). Since the buffercircuit unit 21 is positioned in the width direction center of theseatback S1 in this manner, it is hard for the buffer circuit unit 21 totouch the back of a seated person, even when the back of the seatedperson leans against the seatback S1.

More particularly, when the back of a seated person leans against theseatback S1, the width direction center of the seatback S1 faces a sitepositioned between a right and left pair of erector spinae(specifically, a portion slightly concaved to the ventral side, which isdenoted by sign DP in FIG. 5) of the back of the seated person. FIG. 5is a schematic view showing a positional relationship of the back of aseated person, the heartbeat sensors 11, and the buffer circuit unit 21,when the back of the seated person leans on the seatback S1.Incidentally, in the figure, the hatched regions correspond to sitescorresponding to the erector spinae.

Since the buffer circuit unit 21 is disposed in the width directioncenter of the seatback S1 as above, it becomes hard for the buffercircuit unit 21 to touch the back (strictly, sites corresponding to theerector spinae) of a seated person, when the back of the seated personleans against the seatback S1.

Incidentally, in the present embodiment, in order to more effectivelycontrol the touch of the buffer circuit unit 21 to the back of a seatedperson, the buffer circuit unit 21 is attached to the front face of theseatback S1 so as to be positioned at a predetermined height in theheight direction.

Specifically, the buffer circuit unit 21 is attached so as to bepositioned to a height substantially the same as a height of a sitewhere a spinous process is positioned of the back of a seated person,when the back of the seated person (strictly, a general adult male)leans against the seat back S1. Here, the spinous process refers to aportion curved into a crescent-shape towards the ventral side (theportion denoted by sign SP in FIG. 6), in a spine of a human body. Inother words, when the back of a seated person leans against the seatbackS1, the site corresponding to the spinous process of the back of theseated person is separated from the seatback S1. FIG. 6 is aview-showing a position of a spinous process in the spine of a seatedperson.

As above, in the present embodiment, the buffer circuit unit 21 ispositioned in the center of the seatback S1 in the seat width direction,and disposed in substantially a same position as the spinous process ofa seated person in the height direction. In this manner, it becomes hardfor the buffer circuit unit 21 to touch the back pf a seated person,when the back of the seated person leans against the seat back S1. As aresult, it becomes possible to effectively control the situation thatthe buffer circuit unit 21 touches the back of a seated person to makethe seated person feel a strange touch.

Next, the sensor unit 10B attached to the seat cushion S2 is describedwith referring to FIG. 7. FIG. 7 is a view of a sensor unit 10B attachedto a seat, cushion S2, as viewed from above.

The sensor unit 10B has substantially the same structure as that of thesensor unit 10A attached to the seatback S1, except for the point thatit is attached to a seat cushion S2. That is, the sensor unit 10B has aright and left pair of heartbeat sensors 11, a buffer circuit unit 21,and a base film 14 on which the heartbeat sensors 11 and the buffercircuit unit 21 are placed, as shown in FIG. 7. In addition, a guardring 15 is formed on the outer edge portion of the base film 14.

The right and left pair of heart beat sensors 11 is disposed along theupper face (the contact face with a seated person) of a seat cushion S2via the base film 14. The right and left pair of heartbeat sensors 11 isdisposed symmetrically with having the center position of the seatcushion 32 in the seat width direction as a boundary. In addition, theright and left pair of heartbeat sensors 11 is attached to the seatcushion 32 in a state arranged across a predetermined gap in the seatwidth direction.

Incidentally, a structure of the heartbeat sensor 11 attached to theseat cushion 32 is the same as the aforementioned structure (thestructure of the heartbeat sensor 11 attached to the seatback S1),except for the point that the external configuration of the base unit 13is slightly different as shown in FIG. 7. The following is directed to astructure of a heartbeat sensor 11 attached to a seat cushion S2, inwhich contents other than the above described contents are omitted.

The base film 14 is used to attach the right and left pair of heartbeatsensors 11 to the upper face (the contact face) of the seat cushion S2.The base film 14 has a long shape which is long in the seat widthdirection, and on the both ends in the longitudinal direction thereof,the heartbeat sensors 11 are placed, as shown in FIG. 7. Incidentally,the central, portion in the longitudinal direction of the base film 14is narrowed in the front to back direction, so as to have a slightlynarrower width than the both end portions in the longitudinal direction.The central portion in the longitudinal direction of the base film 14functions as a linking unit 14 c which links between the heartbeatsensors 11. However, this is not a limitation, and it is also possiblethat the linking unit 14 c is not formed, and the right and left pair ofheartbeat sensors 11 is separately attached to the seat cushion S2.

The buffer circuit unit 21 has a circuit substrate 22, an input terminal23, an output terminal 24, and a substrate case 25 for housing them. Asfor circuit structure of the circuit substrate 22, explanation will beomitted, because it is the same as that of the circuit substrate 22 ofthe buffer circuit unit 21 attached to the seatback S1.

As shown in FIG. 7, the circuit substrate 22 is in a state sandwichedbetween the pair of the right and left heartbeat sensors 11 in the seatwidth direction, and disposed in a gap formed between the heartbeatsensors 11. Each of the input terminals 23 built on the both ends in theseat width direction of the circuit substrate 22 is disposed in aposition adjacent to a base unit 13 of a corresponding heartbeat sensor11 (strictly, a portion stretched inward in the seat width direction),as shown in FIG. 7.

In a base unit 13, a terminal portion 12 a of a leading wire 12 enclosedin the portion adjacent to an input terminal 23 (namely, the circuitsubstrate 22) is directly connected to the nearest input terminal 23.This makes a transmission path for an output signal from a heartbeatsensor 11 as short as possible also in the sensor unit 10B attached tothe seat cushion S2, and accordingly, it becomes hard for a noise to besuperposed on an output signal from a heartbeat sensor 11. Thisimproves, as a result, an accuracy in measuring heartbeat of a seatedperson on the basis of an output signal from a heartbeat sensor 11attached to a seat cushion S2.

The guard ring 15 is formed along the outer edge portion of the basefilm 14, over the entire periphery of the outer edge portion. On thelinking unit 14 c provided to the central portion in the seat widthdirection of the base film 14, the guard ring 15 is formed over theentire surface (the upper face) of the portion.

Incidentally, as shown in FIG. 7, each of the heartbeat sensors 11, theguard ring 15, and the circuit substrate 22 are disposed in a horizontalarrangement along the seat width direction, also in the sensor unit 10Battached to the seat cushion S2, similarly as in the sensor unit 10Aattached to the seatback S1. This makes a space for installing eachpiece of the equipment compact.

A sensor unit 10B configured as above appropriately detects a bodypotential of a seated person, when the buttocks of the seated person areput on the seat cushion S2. Particularly, the sensor unit 10B isdisposed in a position where a seated person hardly feels a strangetouch in the seat cushion S2. More specifically, the buffer circuit unit21 including the circuit substrate 22 is attached to the upper face ofthe seat cushion S2 so as to be positioned in the center of the seatcushion S2 in the seat width direction (illustrated by a broken line inFIG. 7).

The buffer circuit unit 21 is attached on the upper face of the seatcushion S2 so as to be within a predetermined range in the front to backdirection. Specifically, the buffer circuit unit 21 is attached so as tobe within a range where the gluteal cleft portion (intergluteal cleft)of a seated person is positioned, in the front to back direction, whenthe buttocks of a seated person (strictly, a general adult male) are puton the seat cushion S2. Here, the gluteal cleft portion refers to aportion concaved toward the ventral side, in the buttocks of a humanbody. In other words, when the buttocks of a seated person are put onthe seat cushion S2, a site corresponding to the gluteal cleft portionis separated from the seat cushion S2.

As above, in the present embodiment, the buffer circuit unit 21 ispositioned in the center of a seat cushion S2, in the seat widthdirection, and disposed within the range where the gluteal cleft portionof a seated person is positioned, in the front to back direction. Thismakes it hard for the buffer circuit unit 21 to touch the buttocks of aseated person when the buttocks of the seated person are put on the seatcushion S2, to allow effectively controlling a situation that a seatedperson feels a strange touch due to a touch of the buffer circuit unit21 to the buttocks of the seated person.

In addition, in the present, embodiment, a range in which the circuitsubstrate 22 attached to the seatback S1 is present in the seat widthdirection (represented by R1 in the figure), and a range in which thecircuit substrate 22 attached to the seat cushion S2 is present in thewidth direction (represented by R2 in the figure) are overlapped witheach other, as shown in FIG. 8. FIG. 8 is a schematic view showing theranges for the circuit substrate 22 to be present in each of theseatback S1 and the seat cushion S2.

In the present embodiment, it becomes possible to properly fit thecircuit substrate 22 to each of the seat cushion and the seatback, forthe above positional relationship. As a result, when each circuitsubstrate 22 is attached, the attachment work thereof become performedcomparatively easily. Incidentally, in the structure illustrated in FIG.8, the range R1 in which a circuit substrate 22 attached to the seatback S1 is present, and the range R2 in which a circuit substrate 22attached to the seat cushion S2 is present completely coincide with eachother in the seat width direction, however, this is not a limitation,and the ranges only need to overlap with each other at least apartially.

Modification Example of Sensor Unit

In the above described embodiment, an example of sensor unit wasreferred to for the explanation. However, the structure of the sensorunit described above is merely an example, and other examples are alsoconceivable. Below described is a sensor units 100A and 100B accordingto a second embodiment (hereinbelow, a modification example) of thepresent invention. The modification example differs from the embodimentdescribed above in terms of structure of the sensor units 100A and 100B,but the modification example and the previous embodiment have the otherpoints in common. That is, a bioinformation measurement device accordingto the modification example has the same function as the bioinformationmeasurement device according to the previous embodiment has, andachieves the same effect as brought about by the function.

In the modification example, a sensor unit 100A is disposed in the seatback S1, as shown in FIG. 9. In addition, a sensor unit 100B is disposedin the seat cushion S2, as shown in FIG. 10. FIG. 9 and FIG. 10 areexplanatory views of the sensor units 100A and 100B according to themodification example, and FIG. 9 is a view of the seat back S1 as viewedfrom the front (ahead), and FIG. 10 is a view of the seat cushion S2 asviewed from above.

Positions to dispose each of the sensor units 100A and 100B aresubstantially the same positions as the positions to dispose the sensorunits 10A and 10B in the previous embodiment (the embodiment illustratedin FIG. 2). In the modification example, a conductive cloth 40 having ashape of rectangular belt is disposed on the backside of each sensorunit 100A and 100B. The conductive cloth 40 is made of a materialpublicly known as a conductive cloth, and sewed together with a skinmaterial constituting the seatback S1 or the seat cushion S2 along theedge of the conductive cloth 40.

A position to dispose the conductive cloth 40 is particularly described.Three conductive cloths 40 are disposed in the central portion in theseat, width direction of the backrest face (the front face) of theseatback S1, as shown in FIG. 9. These three conductive cloths 40 aredisposed symmetrically with respect to the center in the seat widthdirection of the seatback S1. The sensor unit 100A in the side of theseatback S1 is disposed in such a position that the sensor unit 100A isput across all the three conductive cloths 40 in the seat widthdirection. In other words, the sensor unit 100A in the side of theseatback S1 is disposed so as to span all the three conductive cloths40.

In addition, each of the three conductive cloths 40 is formed so as tohave a uniform length in the seat width direction (width). On the otherhand, the center conductive cloth 40 of the three conductive cloths 40is made shorter than the other two conductive cloths 40. Moreparticularly, each of the three conductive cloths 40 is disposed suchthat the individual upper ends are lined up in the height direction. Theindividual upper ends of the three conductive cloths 40 are positionedsomewhat upper than the upper end of the sensor unit 100A, as shown inFIG. 9. On the other hand, the lower end of the center conductive cloth40 of the three conductive cloths 40 is positioned somewhat upper thanthe lower ends of the other two conductive cloths 40.

Position to dispose the conductive cloth 40 in the seat cushion S2 isdescribed. On the seating face (the upper face) of the seat cushion S2,five conductive cloths 40 are disposed in the central portion in theseat width direction of the seat cushion S2, as shown in FIG. 10. Moreparticularly, the five conductive cloths 40 are disposed symmetricallywith respect to the center in the seat width direction of the seatcushion S2. Two of the five conductive cloths 40 (hereinbelow,conductive cloths 40 in the front row) are disposed in the front endportion of the seat cushion S2, and the other three (hereinbelow,conductive cloths 40 in the back row) are disposed in positions slightlyrearward of the conductive cloths 40 in the front row. The sensor unit100B in the side of the seat cushion S2 is disposed in such a positionthat the sensor unit 100B is put across all of the conductive cloths 40in the back row in the seat width direction. In other words, the sensorunit 100B in the side of the seat cushion S2 is disposed so as to spanall the conductive cloths 40 in the back row.

Each of the five conductive cloths 40 is formed so as to have a uniformlength in the seat width direction (width). Further, each of theconductive cloths 40 in the back row is disposed such that theindividual front ends are lined up in the front to back direction.Incidentally, the front end of each of the conductive cloths 40 in theback row is positioned somewhat forward of the front end of the sensorunit 100B, as shown in FIG. 10. On the other hand, the front end portionof each of the conductive cloths 40 in the front row goes around to thefront end face of the seat cushion S2.

Below described are structures of the sensor units 100A and 100Baccording to the modification example. First, a structure of the sensorunit 100A in the side of the seatback S1 is described with referring toFIG. 11. FIG. 11 is a view of the sensor unit 100A in the side of theseat back S1, as viewed from the front (ahead).

The sensor unit 100A has a ground electrode unit 110, a right and leftpair of heartbeat sensors 111, a buffer circuit unit 121, and a basefilm 114, as shown in FIG. 11. In addition, a guard ring 115 is formedon the base film 114.

The ground electrode unit 110 regulates a reference potential (namely, 0V) at the time of detecting a body potential of a seated person by theheartbeat sensor 111, and is disposed in a position sandwiched betweenthe right and left pair of heartbeat sensors 111. This ground electrodeunit 110 is used for the purpose of confirming a potential differencewith the heartbeat sensor 111, and for the purpose of controllingoccurrence of noise caused by static electricity or the like. Structureof the ground electrode unit 110 is the same as that of the heartbeatsensor 111. Particularly, the ground electrode unit 110 is formed of anelectrode in a shape of a sheet, and has a substantially rectangularexternal configuration, as shown in FIG. 11. Incidentally, asillustrated in FIG. 9, the ground electrode unit 110 is disposed suchthat the center position in the right to left direction coincides withthe center position in the seat width direction of seatback S1.

The ground electrode unit 110 is formed of the leading wire 112 and thebase unit 113 which encloses the leading wire 112. The base unit 113 hasa laminated structure similar to that of the base unit 13 of theheartbeat sensor 11 according to the previous embodiment (the laminatedstructure as illustrated in FIG. 3). In the central portion of the baseunit 113, a long hole 113 h elongated in the vertical direction isformed. The leading wire 112 is wired regularly in the base unit 113.Specifically, the leading wire 112 constituting the ground electrodeunit 110 has a portion wired along the edge of the ground electrode unit110 which has a substantially rectangular shape, a portion wired in amanner surrounding the long hole 113 h described above, and a portionwired to interlink these portions, along the vertical direction or theseat width direction. In the leading wire 112, a terminal portion 112 awhich is the most downwardly positioned extends downward toward thebuffer circuit unit 121, as shown in FIG. 11. Then, the terminal portion112 a of the leading wire 112 is joined to an input terminal 123 of acircuit substrate 122 provided to the buffer circuit unit 121.

The right and left pair of heartbeat sensors 111 is disposedsymmetrically with having the center position in the seat widthdirection of the seatback S1 as a boundary, and sandwiches the groundelectrode unit 110 therebetween. More particularly, the right and leftpair of heartbeat sensors 111 forms an external configuration ofapproximate C-letter shapes facing each other. The ground electrode unit110 is disposed between the right and left pair of heartbeat sensors 111which is accordingly disposed in a manner surrounding the four sides ofthe ground electrode unit 110.

A structure of the heartbeat sensor 111 according to the modificationexample is described. Each of the heartbeat sensors 111 is formed of aleading wire 112 and a base unit 113 that encloses the leading wire 112,similarly as the heartbeat sensor 11 according to the previousembodiment. The base unit 113 is a sheet-shaped member which defines anouter shape of the heartbeat sensor 111, and has the same laminatedstructure as that of the base unit 13 of the heartbeat sensor 11according to the previous embodiment (the laminated structureillustrated in FIG. 3). Arcuate notches 113 x are formed inpredetermined portions in the outer edge portion of the base unit 113(specifically, the end portion in the outer side in the seat widthdirection, and the lower end portion). In this manner, the base unit 113bends without accompanied by a wrinkle, when the back of a seated personleans against the seat back S1. This suppresses, as a result, aninfluence to the heartbeat sensor. 111 given when the back of a seatedperson leans against the seatback S1 (specifically, a bend of theleading wire 112, and a disconnection caused thereby).

A leading wire 112 constituting a heartbeat sensor 111 has a portionwired along the edge of the heartbeat sensor 111 in the base unit 113,and a portion wired in a lattice shape inside the portion. In theleading wire 112 wired along the edge of heartbeat sensor 111, a portionpositioned in the inner end portion in the seat width direction of theheartbeat sensor 111 is bent along the periphery of the ground electrodeunit 110, in a manner, deflecting from the ground electrode unit 110, asshown in FIG. 11. A portion of the leading wire 112 wired along the edgeof the heartbeat sensor 111 (more strictly, the leading wire 112positioned in the inner end portion in the seat width direction of theheartbeat sensor 111) constitutes a terminal portion 112 a. As shown inFIG. 11, the terminal portion 112 a goes around to the lower position ofthe ground electrode unit 110, and extends curvedly downward toward thebuffer circuit unit 121, to finally join to the input terminal 123 ofthe circuit substrate 122 which is provided to the buffer circuit unit121.

The base film 114 is a substrate in a shaped of a sheet for attachingthe ground electrode unit 110 and each of the right and left pair ofheartbeat sensors 111 to the front face (the backrest face) of theseatback S1. In the modification example, the base film 114 forattaching the ground electrode unit 110, and the base film 114 forattaching each of the heartbeat sensors 111 are continuous andintegrated into a sheet as a whole.

The base film 114 according to the modification example is molded intoan approximate H-letter shape. The heartbeat sensors 111 are adhered tothe front face of the side portions (the vertically long portions) ofthe H-letter shaped base film 114, and the ground electrode unit 110 isadhered to the front face of the central portion. As above, in themodification example, the ground electrode unit 110 and the right andleft pair of heartbeat sensors 111 form a unit by being adhered to thesingle sheet of base film 114.

Incidentally, in the base film 114, a notch with a vertically longslit-shape (hereinbelow, vertical notch 114 y) is formed between theupper end portion of the portion to which the left heartbeat sensor 111is adhered and the upper end portion of the portion to which the rightheartbeat sensor 111 is adhered. In addition, in the edge portion of thebase film 114, in portions adjacent to the notches 113 x formed on thebase unit 113 of the heartbeat sensor 111, similarly arcuate notches 114x are formed. Specifically, as shown in FIG. 11, a notch 114 x is formedin the lower end portion of a portion to which a heartbeat sensor 111 isadhered, of the base film 114. In addition, three notches 114 x arrangedin the vertical direction are formed in a side end portion (strictly, anouter end portion in the seat width direction) of a portion to which aheartbeat sensor 111 is adhered. Incidentally, among the three notches114 x arranged in the vertical direction, the notch 114 x in theuppermost position is formed in the same position as that of the lowerend portion of the aforementioned vertical notch 114 y, in the heightdirection. That is to say, the vertical notch 114 y is formed so as toreach the position in which the uppermost position notch 114 x isformed, in the height direction.

In the base film 114, the lower end portion of the portion to which theleft side heartbeat sensor 111 is adhered, and the lower end portion ofthe portion to which the right side heartbeat sensor 111 is adhered areseparated from each other in the seat width direction. In themodification example, the buffer circuit unit 121 is disposed, utilizinga space between the separated lower end portions, as shown in FIG. 11.Incidentally, the buffer circuit unit 121 disposed in the space ispositioned inner than the outermost portion of the outer edge of thebase film 114, as shown in FIG. 11. As also shown in the same figure,the base film 114 is provided with a linking unit 114 b that interlinksbetween the separated lower end portions.

The guard ring 115 is formed on the base film 114, in a mannersurrounding the ground electrode unit 110 and each of the right and leftpair of heartbeat sensors 111. More specifically, the guard ring 115disposed around the heartbeat sensor 111 is formed over the entireperiphery of the edge of the base unit 113 of the heartbeat sensor 111.The guard ring 115 disposed around the ground electrode unit 110 isformed over the entire periphery of the edge of the base unit 113 of theground electrode unit 110. In the ground electrode unit 110, the guardring 115 is also formed around the long hole 113 h, as shown in FIG. 11.

The buffer circuit unit 121 is positioned between the right and leftpair of heartbeat sensors 111, and at the same time, disposed in a lowerposition from the ground electrode unit 110. More specifically, thebuffer circuit unit 121 is disposed between the lower end portion of theportion to which the left side heartbeat sensor 111 is adhered and thelower end portion of the portion to which the right side heartbeatsensor 111 is adhered, in the base film 114. Incidentally, in theposition in which the buffer circuit unit 121 is disposed, the linkingunit 114 b of the base film 114 is provided. Strictly, in themodification example, the buffer circuit unit 121 is disposed in therear side (the backside) of the linking unit 114 b, as shown in FIG. 11.This allows the linking unit 114 b to function as a controlling unitthat controls a forward movement of the buffer circuit unit 121.

Next, a structure of the sensor unit 100B in the side of the seatcushion S2 is described with referring to FIG. 12. FIG. 12 is a view ofa sensor unit 100B in the side of the seat cushion S2, as viewed fromabove.

The sensor unit 100B basically has the same structure as that of thesensor unit 100A attached to the seatback S1, except for the point thatit is attached to a seat cushion S2. That is, the sensor unit 100B has aground electrode unit 110, a right and left pair of heartbeat sensors111, a buffer circuit unit 121, and a base film 114, as shown in FIG.12. In addition, a guard ring 115 is formed on the base film 114. Theseunit components have the same structures as those of the partsconstituting the sensor unit 100A in the side of the seatback S1, exceptfor shapes or disposed positions.

The ground electrode unit 110 has a horizontally long rectangular shapeas illustrated in FIG. 12. As illustrated in FIG. 10, the groundelectrode unit 110 is disposed such that the center position in theright to left direction thereof coincides with a center position in theseat width direction of seat cushion S2. In the central portion of abase unit 113 constituting the ground electrode unit 110, a long hole113 h elongated in the front to back direction is formed. A leading wire112 enclosed in the base unit 113 is wired in a zigzag manner.Incidentally, in the leading wire 112, the terminal portion 112 apositioned immediately before the long hole 113 h extends forward towardthe buffer circuit unit 121, and joins to the input terminal 123 of thecircuit substrate 122 in the buffer circuit unit 121.

Furthermore, arcuate notches 113 x are formed in a rear end portion ofthe base unit 113. This allows the base unit 113 to bend without beingaccompanied by a wrinkle, when the buttocks of a seated person are puton the seat cushion S2. As a result, an influence to the groundelectrode unit 110 given when a seated person is seated on the seatcushion S2 (specifically, a bend of the leading wire 112, and adisconnection caused thereby) is suppressed.

The right and left pair of heartbeat sensors 111 is disposedsymmetrically with having the center position in the seat widthdirection of the seat cushion S2 as a boundary, and sandwiches theground electrode unit 110 therebetween. More particularly, the right andleft pair of heartbeat sensors 111 forms an external configuration ofapproximate L-letter shapes facing each other. Then, between the rearend portions of the heartbeat sensors 111, the ground electrode unit 110is disposed, as shown in FIG. 12.

In addition, arcuate notches 112 x are formed on predetermined portionsin edge portions, specifically, in the fore end portion and the rear endportion, of the base unit 113 which constitutes each of the heartbeatsensors 111. Such notches 113 x achieve the same effect as that achievedby the notch 113 x provided to the base unit 113 of the ground electrodeunit 110 described above. Inner side portion of the base unit 113 ofeach of the heartbeat sensors 111, a long hole 113 h elongated in thefront to back direction is formed. This long hole 113 h is formed insubstantially the same position as the position in which the notch 113 xis formed, in the seat width direction, as shown in FIG. 12.

The leading wire 112 constituting the heartbeat sensor 111 has a portionwired along the edge of a heartbeat sensor 111 in the base unit 113, andinside the portion, a portion wired in an X-letter shape. Incidentally,in the leading wire 112 wired along the edge of a heartbeat sensor 111,the portions positioned in the inside end portion in the seat widthdirection of the heartbeat sensor 111 are bent along the periphery ofthe ground electrode unit 110, in a manner deflecting from the groundelectrode unit 110, as shown in FIG. 12. A portion of the leading wire112 wired along the edge of a heartbeat sensor 111 (more strictly, theleading wire 112 positioned at the inside end portion in the seat widthdirection of the heartbeat sensor 111) constitutes a terminal portion112 a. Then, as shown in FIG. 12, the terminal portion 112 a goes aroundto the fore position of the ground electrode unit 110, extends curvedlyforward toward the buffer circuit unit 121, and finally joins to aninput terminal 123 of the circuit substrate 122 in the buffer circuitunit 121.

The base film 114 is formed of a sheet, in which a portion to which theground electrode unit 110 is adhered, and portions to which theheartbeat sensors 111 are adhered are continuous and integrated. Thebase film 114 is shaped into an approximate downward U-letter shape. Theheartbeat sensors 111 are adhered to the upper face of the side portionsof the downward U-letter shaped base film 114, and the ground electrodeunit 110 is adhered to the upper face of the central portion. Inaddition, in the edge portion of the base film 114, in portions adjacentto the notches 113 x formed on the base unit 113 of the ground electrodeunit 110 and the heartbeat sensor 111, similarly arcuate notches 114 xare formed.

In the base film 114, the fore end portion of the portion to which theleft side heartbeat sensor 111 is adhered, and the fore end portion ofthe portion to which the right side heartbeat sensor 111 is adhered areseparated from each other in the seat width direction. Then, as shown inFIG. 12, the buffer circuit unit 121 is disposed, utilizing a spacebetween the separated fore end portions. Incidentally, the buffercircuit unit 121 disposed in the above described space is positionedinward to the outermost portion of the outer edge of the base film 114,as shown in FIG. 12. As also shown in the same figure, the base film 114is provided with a linking unit 114 b that interlinks between theseparated fore end portions. By disposing the buffer circuit unit 121 inthe lower side (the backside) of this linking unit 114 b, an upwardmovement of the buffer circuit unit 121 is controlled by the linkingunit 114 b.

The guard ring 115 is formed over the entire periphery of the edge ofthe base unit 113 of each of the ground electrode unit 110 and theheartbeat sensors 111, and at the same time, formed also around the longholes 113 h provided to the inner side region of each of the base units113.

The Other Embodiments

In the embodiment described above, a structure of the bioinformationmeasurement device of the present invention has been described withreferring to an example. However, the embodiment described above doesnot limit the present invention, but is merely an example forfacilitating understanding of the present invention. That is, thepresent invention may be modified or improved without deviated from thegist thereof, and the present invention naturally involves equivalentsthereof.

In the above described embodiment, a heartbeat was measured as abioinformation of a seated person. However, this is not a limitation,and the present invention may also be applied to a case where abioinformation other than a heartbeat, such as a body temperature, abrain wave, a respiration waveform or the like is measured.

In the above described embodiment, the circuit substrate 22 was providedtherein with the differential amplifier 30 that amplified an outputsignal (an electric signal) from a heartbeat sensor 11, and at the sametime, provided with the impedance adjustment unit 31 for adjustingimpedance values between the heartbeat sensors 11. However, this is nota limitation, and the structure may also be such that only thedifferential amplifier 30 is provided, and the impedance adjustment unit31 is not provided in the circuit substrate 22.

In addition, in the above described embodiment, the wiring pattern ofthe leading wire 12 in a heartbeat sensor 11 was described withreferring to an example (specifically, the example illustrated in FIG. 2or FIG. 7). However, a wiring pattern of the leading wire 12 mayarbitrarily be set, as long as it can preferably detect a body potentialof a seated person.

In the embodiment described above, a right and left pair of heartbeatsensors 11 was attached individually to the seatback S1 and the seatcushion S2. However, number of the heartbeat sensor 11 is netparticularly limited, and the structure may be such that each oneheartbeat sensor 11 is attached to the seatback S1 and the seat cushionS2. The structure may also be such that a heartbeat sensor 11 isattached only to the seatback S1.

REFERENCE SIGNS LIST

1: Heartbeat measurement device (Bioinformation measurement device)

10A, 10B, 100A, 100B: Sensor unit

11, 111: Heartbeat sensor (Sensor)

12, 112: Leading wire

12 a, 112 a: Terminal portion

13, 113: Base unit

13 a: Lowermost layer

13 b: Intermediate layer

13 c: Uppermost layer

13 x, 113 x: Notch

14, 114: Base film

14 a, 14 b, 14 c, 114 b: Linking unit

14 x, 114 x: Notch

114 y: Vertical notch

15, 115: Guard ring

21, 121: Buffer circuit unit

22, 122: Circuit substrate

23, 123: Input terminal

24: Output terminal

25: Substrate case

30: Differential amplifier (Amplification unit)

31: Impedance adjustment unit

40: Conductive cloth

110: Ground electrode unit

113 h: Long hole

C: Cable

S: Vehicle seat (Seat)

S1: Seatback

S2: Seat cushion

S3: Headrest

1. A bioinformation measurement device for measuring a bioinformation ofa seated person who is seated on a seat, comprising: a sensor whichoutputs an electric signal according to the bioinformation, andcomprises a leading wire constituting a transmission path for theelectric signal, and a circuit substrate comprising an input terminalprovided to receive the electric signal from the sensor, and anamplification unit which amplifies the electric signal input to theinput terminal, wherein the sensor and the circuit substrate aredisposed in positions adjacent to each other in the seat, and in thesensor, a terminal portion of the leading wire come out from a portionadjacent to the circuit substrate is connected to the input terminal ina state abutting the input terminal.
 2. The bioinformation measurementdevice according to claim 1, wherein the circuit substrate is attachedto the seat so as to be positioned in the width direction center of theseat.
 3. The bioinformation measurement device according to claim 1,comprising a plural number of the sensor, wherein the plural number ofthe sensor are arranged across a gap in the width direction of the seat,and the circuit substrate is disposed within the gap in a statesandwiched between the sensors.
 4. The bioinformation measurement deviceaccording to claim 1, comprising a guard ring disposed in a mannersurrounding the sensor, wherein the sensor is disposed on a face, whichcome in contact with the seated person, of the seat, and the sensor, theguard ring, and the circuit substrate are disposed in a state arrangedalong the width direction of the seat.
 5. The bioinformation measurementdevice according to claim 2, wherein the circuit substrate is attachedso as to be positioned in the width direction center of a seatbackprovided to the seat.
 6. The bioinformation measurement device accordingto claim 2, wherein the circuit substrate is attached so as to bepositioned in the width direction center of a seat cushion provided tothe seat.
 7. The bioinformation measurement device according to claim 1,wherein the sensor and the circuit substrate are attached individuallyto the seat cushion and the seatback provided to the seat, and a rangewhere the circuit substrate attached to the seat cushion is present inthe seat width direction, and a range where the circuit substrateattached to the seatback is present, overlap with each other in thewidth direction.